The invention relates to the field of control devices with several stable positions, especially for motor vehicles. More precisely, what are involved are devices intended to be used as on-off switches, changeover switches, pushbuttons, etc.
Bistable mechanical switches are already known (air-conditioning controls, warning light controls, etc.) comprising a finger 3 and a heart-shaped cam 5. Their principle is illustrated diagrammatically in FIGS. 1a and 1b. When these switches are actuated, the finger 3 and the cam 5 are in shifted in translation, with respect to one another (movement D, FIG. 1a). In the course of this translation, the finger 3 is guided around the cam 5, on a cam track in a single direction, with an auxiliary movement (movement A, FIG. 1b) on the flat, in a plane parallel to the direction of operation of the button of the switch. In order to follow the cam track, the finger 3 undergoes rotation about an axis perpendicular to that of translation (movement D). The finger 3 of this type of device is, moreover, permanently applied, by virtue of a spring 7, onto the bottom of the cam track which features a variable altitude and implies a shifting of the finger 3 perpendicularly to the direction of operation of the button of the switch (movement B, FIG. 1a).
One object of the invention is to furnish a control device with several stable positions, less bulky than those described above.
This object is achieved by virtue of a control device with several stable positions, comprising a cam and a finger, the finger traveling along a cam track around the cam, when the finger and the cam are moved with respect to one another in translation, the cam track exhibiting curvature about an axis of rotation parallel to the axis of the translation in order, during the translation, to move the finger and the cam in rotation with respect to one another, wherein the rotational movement of the cam and of the finger, with respect to one another, is achieved by virtue of the fact that the finger and the cam each respectively consist of a cylindrical ring, these two rings being coaxial and capable of a rotational movement with respect to one another. In fact, with devices such as buttons themselves often having an axisymmetric cylindrical shape, the two rings can easily be incorporated into the device. Moreover, with the two rings being coaxial, one situated inside the other, the device according to the invention is remarkably compact.
Advantageously, the finger is guided on the cam track by virtue of a stud mounted on an elastic tab and made of the same material as the ring on which it is located. This makes it possible, by not using a strip or spring to apply the finger to the bottom of the cam track (as in the prior art presented above), to limit the number of pieces of the device. This facilitates assembly thereof, and makes it less expensive to manufacture.
Advantageously also, the control device according to the invention comprises at least one end stop for taking up the substantial forces exerted on the device, along the translation axis. By virtue of this end stop, the user can exert very substantial force parallel to the translational axis of the device without damaging the cam or the finger. The number of end stops may be greater than 1.
Advantageously, the device according to the invention includes a spring providing a permanent force for bringing the finger into abutment on the cardioid cam, in the stable positions.
According to another aspect, the invention is a cigar lighter.
Cigar lighters including pushbuttons are already known, on which it is possible to press or which are pulled. The operation of a cigar-lighter button of the prior art, of this type, is illustrated in FIGS. 2a and 2d. It protrudes from the dashboard on which the cigar lighter is mounted, when the latter is not being used (FIG. 2a). This position corresponds to a rest position. Pressure is exerted on the pushbutton in order to set the cigar lighter to heating mode (FIG. 2b). The button remains pushed in during the period of heating in a power-supply unit (FIG. 2c). At the end of the heating period, the button rises back up and again becomes proud of the dashboard so that the user can use the heating assembly integral with the button (FIG. 2d). This position of the button is identical to the rest position described above (FIG. 2a). In this position, the user can also pull on the button in order to extract the heating assembly from the power supply unit of the cigar lighter so as to use the unit as a power socket.
This type of control device exhibits the drawback of protruding, in rest position, from the surface on which it is mounted.
Another object of the invention is to furnish a cigar lighter not exhibiting this drawback.
This object is achieved by virtue of a cigar lighter intended to be mounted on a dashboard, especially of a motor vehicle, comprising a power-supply body and a removable, heating pushbutton, and including a pushing surface, the button being able to occupy a first position in the unit, in which it is at least partly projecting with respect to the sweep of the dashboard, in order to be grasped and extracted from the unit, and a second position in which the button can be heated, wherein the button is, moreover, able to take up a third, stable position in which it is not heated and where the pushing surface follows the sweep of the dashboard.
Advantageously then, the cigar lighter according to the invention further includes a cam and a finger, the finger traveling along a cam track around the cam, when the finger and the cam are moved with respect to one another, in translation. Also advantageously, the cam track features a curvature around an axis of rotation parallel to the axis of the translation for moving the finger and the cam in rotation with respect to one another during the translation.
Advantageously, in this case, the cigar lighter comprises a gripping button fixed to the finger with the aid of a pivot link formed by virtue of countersunk clips. This makes it possible to limit the number of pieces to be assembled in order to form a button in accordance with the present invention.
Advantageously, the pushbutton of the cigar lighter is in three parts which are a gripping button, a finger and a cam.